title: In vitro regulation of FcepsilonRIalpha expression on human basophils by IgE antibody.
abstract: In vivo studies suggested the possibility of an IgE-dependent regulation of high-affinity (FcepsilonRI) IgE receptor expression on basophils. The current studies extend these observations to in vitro cultures of human basophils. Incubation of basophils for 3 to 4 weeks resulted in a slow dissociation of IgE antibody, during which time FcepsilonRI expression decreased, as measured by flow cytometry using the anti-FcepsilonRIalpha monoclonal antibody, 22E7, or by measuring FcRIalpha mass by Western blotting of whole-cell lysates. Culture of basophils with IgE resulted in upregulation of FcepsilonRIalpha expression by both flow cytometry and Western blotting of whole-cell lysates. Upregulation followed a linear time course during 2 weeks of culture. The relative increase in FcepsilonRIalpha density depended on the starting density; with starting densities of FcepsilonRIalpha of 10,000 to 170,000 per basophil, the upregulation varied 20- to 1.1-fold, respectively. Upregulation occurred in high-purity basophils, was not influenced by IgG at concentrations up to 1 mg/mL, and was inhibited by dimeric IgE. Heat-inactivated IgE was less effective and the monoclonal antibody CGP51901 that prevents IgE binding to FcepsilonRIalpha blocked the ability of IgE to induce upregulation. The dose-response curve for IgE-induced upregulation had an effective concentration50 of 230 ng/mL. Although the receptor through which IgE induces this upregulation is not yet known, several characteristics suggest that the upregulation is mediated by IgE interacting through FcepsilonRIalpha itself.
authors.affiliation: Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA.
authors.forename: D
authors.initials: D
authors.lastname: MacGlashan
authors.forename: J
authors.initials: J
authors.lastname: McKenzie-White
authors.forename: K
authors.initials: K
authors.lastname: Chichester
authors.forename: B S
authors.initials: BS
authors.lastname: Bochner
authors.forename: F M
authors.initials: FM
authors.lastname: Davis
authors.forename: J T
authors.initials: JT
authors.lastname: Schroeder
authors.forename: L M
authors.initials: LM
authors.lastname: Lichtenstein
mesh_terms: D000911:Antibodies, Monoclonal; D001491:Basophils / Q000276:immunology*; D015153:Blotting, Western; D002478:Cells, Cultured; D019281:Dimerization; D015536:Down-Regulation; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism / Q000494:pharmacology*; D007074:Immunoglobulin G / Q000494:pharmacology; D017455:Receptors, IgE / Q000378:metabolism*; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D017455:Receptors, IgE; D007073:Immunoglobulin E